Identification: Euglandina rosea is a terrestrial
snail with a long and slender body. It can be recognized by its shell,
which is pinkish and almost translucent. The shell is usually two
to three inches in length, six centimeters in height and two centimeters
in width (only Achatina fulica Bowdich is larger). The lips,
which are elongated and protrude like tentacles, contain chemical receptors
that are used to track prey by following their mucus trails. When it
has located its prey, it consumes smaller species whole, while larger ones
are manuevered in such a way that their soft parts are exposed for easier
extraction. Observation of feeding behavior demonstrates that E.
rosea prefers smaller snails, especially if the shell can be swallowed
whole, suggesting that a component of feeding behavior is dictated by calcium
demands.

Original Distribution: E. rosea is native
to the southeastern United States.

Site and Date of Introduction: E. rosea was
first introduced to the Hawaiian Islands in 1955 by the Hawaii State Department
of Agriculture to control the giant African snail (Achatina fulica
Bowdich), an exotic agricultural pest that was deliberately introduced
for garden decoration in 1936. Since 1955, E. rosea has been
introduced to more than 20 oceanic islands as a biological control agent
for A. fulica and other snail pest species. Biological control is
often used to decrease populations of detrimental species to levels where
their impacts are insignificant.
Mode(s) of Introduction: E. rosea has been deliberately
introducted to numerous areas to control A. fulica, even though
there is no indiction that E. rosea has reduced the populations
of A. fulica anywhere.

Reason(s) Why it
has Become Established:Human activities often
provide a very efficient dispersal pathway for exotic species. E. rosea introduction to Hawaii
was deliberate. A species that is deliberately introduced often has
a greater chance of becoming established, integrated and subsequently invasive
than those that are inadvertently introduced. Deliberately introduced
species are often able to establish because a large number of individuals
are often released. In addition, these individuals usually receive
a great amount of care and attention to promote their growth and reproduction.

E. rosea
has become established because it is an r-selected species with generalist
food requirements, wide habitat tolerance and efficient dispersal.
In addition, the fact that E. rosea is native to the Southeastern
United States and was introduced to areas with a similar environment enhanced
its chances of becoming established.

E. rosea
is a cross-fertilizing hermaphroditic species that lay approximately 25-40
eggs a year. It has a much higher reproductive rate than Hawaii’s
endemic land snails, which reach sexual maturity at about five years and have
a low reproductive rate, giving birth to an average of only four or five
live young a year.

Although E.
rosea seems to have a preference for endemic snails, it is certainly
not a food specialist. It will not hesitate to consume other wolfsnails.
Upon hatching, young wolfsnails immediately look for prey and smaller siblings
are often eaten. The wolfsnail further supplements its diet with the
numerous slug species found in Hawaii as well as the other non-indigenous
snails that were introduced for control of A. fulica.

E. rosea
is a habitat generalist and lives in both disturbed and undisturbed areas.
It has expanded its range from disturbed areas infested with A. fulica
and spread into the native forests, into higher elevations where Hawaiian
endemic tree snails are found. Although considered a terrestrial invertebrate,
in its native habitat, it has been seen crawling up trees and has been known
to go underwater in search of its prey.

Ecological
Role: Land invertebrate. E. rosea is a source of
food for numerous species. In Hawaii, it is preyed upon by the Norway
rat (Rattus norvegicus), and the black rat (Rattus rattus).
E. rosea serves as an important source of calcium for birds and
is especially important during the breeding season when birds need a calcium-rich
diet for eggshell formation. However, it is unclear whether E.
rosea fills this role in Hawaii since the majority of Hawaiian birds
are insectivorous.

Benefit(s):
Of the fourteen snail species introduced to Hawaii for the biological
control of A. fulica, only three have become established: Euglandina
rosea, Gonaxis kibweziensis and Gonaxis quadrilateralis.
Among these three, only
E. rosea has become invasive and has exerted a major ecological impact
on the native Hawaiian snail fauna. The presence of E. rosea
has probably played a role in keeping the populations of G. kibweziensis
and G. quadrilateralis down. Since all three species occupy the
same ecological niche in Hawaii, which lacks an indigenous predatory snail,
competition for resources is inevitable. In such a competition, E.
rosea (the larger, more adaptable species) would likely emerge victorious
by consuming and outcompeting the other two species. However, the availability of these
non-indigenous snails has probably also allowed E. rosea to exist
in higher numbers than would otherwise be possible.

Threat(s): Currently, the greatest threat to terrestrial
snails in Hawaii has been the exotic rosy wolfsnail. The native snail
fauna of the Hawaiian Islands is rapidly disappearing. The terrestrial
snail fauna consists of 11 families, most of which have suffered considerable
extinction. The native land snails affected include: the family Amastridae,
endemic to Hawaii, only ten species of the original 300 remain; in the
genus Carelia, all 21 species endemic to Kauai are believed to
be extinct; in the genus Achatinella, 80 percent of the 41 species
found on Oahu have become extinct; 50 percent of the species in the genus
Partulina, found on Molokai, Maui, Oahu, Lanai and the Big Island
of Hawaii have been devastated.

Since its
introduction, the rosy wolfsnail has become an out-of-control invasive that
has developed a taste for the island’s native snail species, driving several
to extinction
and pushing the entire genus Achatinella onto the US endangered species list.
Human activities have further introduced E. rosea to other islands,
with similar devastating effect on the local snail fauna. In Mauritius,
24 of 106 endemic snails became extinct, and on the island of Moorea in French
Polynesia, E. rosea was responsible for the extinction of seven endemic
snails in the genus Partulina.

Control Level Diagnosis: Highest Priority.
According to the Global Invasive Species Database, E. rosea is considered
one of the world's 100 worst invaders. The presence of E. rosea has
been strongly linked to the extinction and decline of numerous snail species
in every area where it has been introduced.

Control Method: Conservationists
are working to prevent the further spread of E. rosea. Exclosures
have been built in Hawaii and French Polynesia to prevent E. rosea from
attacking native tree snails. These barriers are somewhat successful
but require constant monitoring and maintenance. A toxic bait using
snails from the genus Pomacea is being tested in Hawaii.